1. Field of the Invention
The present invention relates to technique by which plural users share the identical space.
2. Related Background Art
An attempt to shoot or photograph a real space by a camera mounted on a movable body such as a vehicle or the like and then represent the shot real space as a virtual space by using a calculator on the basis of real-shot image data obtained has been proposed. For example, “Image-Based Cybercities by Using Vehicle-Mounted Cameras” Endo, Katayama, Tamura, Hirose, Watanabe, Tanikawa (IEICE (Institute of Electronics, Information and Communication Engineers) Societies, PA-3-4, pp. 276-277, 1997), “Building Image-Based Cybercities by Using Vehicle-Mounted Cameras (2)—Creating Wide-Range Virtual Environment Taking Into Consideration Cameras and 3D Sensors” Hirose, Watanabe, Tanikawa, Endo, Katayama, Tamura (Collected Papers of The Virtual Reality Society of Japan, 2nd convention, pp. 67-70, 1997), and the like are quoted.
As a method of representing the shot real space as the virtual space on the basis of the real-shot image data obtained by the camera mounted on the movable body, a method of reproducing a geometric model of the real space on the basis of the real-shot image data and then representing the model by using CG (computer graphics) technique is quoted, but this method has the limit in point of, e.g., accuracy, fineness and reality of the model. On one hand, in recent years, IBR (Image-Based Rendering) technique to represent a virtual space by using real-shot image data without reproducing any model has come under the spotlight. Here, the IBR technique is the technique to generate an image which is viewed from an arbitrary viewpoint, on the basis of plural real-shot image data. Since the IBR technique is based on the real-shot image data, it is possible to represent a real virtual space.
In order to build by using the IBR technique a virtual space where a user (experimenter) can walk through (a walk-through operation), it is necessary to generate and present the image according to the position of the user in the virtual space. Thus, in this type of system, each image frame of the real-shot image data is correlated with the position in the virtual space and thus obtained data is stored beforehand, the corresponding image frame is obtained on the basis of the user's position in the virtual space and the direction of user's line of sight, and the obtained image frame is then reproduced.
As a method of obtaining the position data in the real space, it is popular to use a method which utilizes an artificial-satellite positioning system such as GPS (Global Positioning System) used in a car navigation system or the like. Moreover, as a method of correlating position data obtained from the GPS or the like with real-shot image data, a method which uses a time code added to the real-shot image data has been proposed (Japanese Patent Application Laid-Open No. 11-168754). In this method, time data included in the position data is correlated with the time code added to each frame of the real-shot image data, thereby correlating each frame of the real-shot image data with the position data.
In the such like virtual space where the user can walk through, in order to enable the user to view a desired angle at each viewpoint position, it is thought that the image at each viewpoint position is stored beforehand in the form of a panoramic real-shot image capable of covering the range wider than an angle of view at the time of reproduction, and then the partial image to be reproduced is cut out and displayed on the basis of the user's viewpoint position and the direction of user's line of sight in the virtual space.
However, since such a conventional apparatus is independently set, the image corresponding to designated viewpoint information cannot be shared by plural users respectively viewing different screens. In other words, the plural users cannot achieve a real-world quasi-experience at the identical viewpoint.